Device for supplying lubricating-and-cooling agent to cutting tools

ABSTRACT

The herein-proposed device includes a housing (1) provided with a hole (2) adapted to receive an arbor (3) carrying a cutting tool (4), a seal (8) mounted on the housing (1) in the zone of interaction between the cutting tool (4) and a workpiece (6) to be machined, pipings (16, 18) adapted for the supply and withdrawal of coolant, respectively, and a chip disposal opening (10). The device is provided with a safety valve (19) installed on the coolant supply piping (18). The housing (1) is provided with a seal (5) arranged in the zone of location of the arbor (3). The chip disposal opening (10) and a space (9) of the housing (1) are arranged on the opposite sides with respect to an end face (11) of the housing (1) in the zone of interaction between the cutting tool (4) and the workpiece (6) to be machined.

FIELD OF THE INVENTION

The present invention relates generally to metal machining and morespecifically to a device for supply of a coolant to cutting tools.

The herein-proposed invention finds particular utility when employed fordeep-hole drilling with the aid of twist drills.

BACKGROUND OF THE INVENTION

At the present time, the practice of deep-hole drilling with the use oftwist drills is characterized by low cutting speeds and fast wear of thecutting tool. This is concerned with the fact that with greater drillingdepths, difficulties are encountered in supplying coolant to the cuttinglips of the twist drill.

Widely known in the present state of the art is a device for the supplyof a lubricating-and-cooling agent (hereinafter referred to as "coolant"to the comprising a bath filled with coolant, wherein a workpiece to bemachined is accommodated and secured so that the level of coolant ishigher than the hole to be drilled (cf., a textbook "Unit-built MachineTools" by G. I. Melamed et al., 1964, "Mashgiz" Publishers, Moscow, (inRussian).

With low drilling depths, coolant readily flows to the hole beingmachined, whereby the drill cutting lip are lubricated and cooled down.In deep-hole drilling, the drill operates virtually dry because a steam"cushion" produced at the drill point prevents coolant from getting tothe cutting lips, and the twist drill, which operates as a "screw pump",tends to pump coolant out of the hole. The joint action of these factorsresults in the need to withdraw, at regular intervals, the drill fromthe hole being machined, thus reducing the machining efficiency.

Known presently is another device for the supply of coolant underpressure to the cutting tool in the machining zone, comprising a housinghermetically sealed by a cover having an opening provided with a sealand adapted to receive an arbor carrying the cutting tool (cf."Proceedings of Higher Educational Institutes", "Machinostroyeniye"Publishers, Issue No. 12, 1969, Moscow, "Cutting Processes Under HighStatic Pressures of Coolant" by V. M. Yaroslavtsev, V. V. Sabel'nikov,pp. 172-176 (in Russian). The workpiece to be machined is arrangedinside the housing. Coolant under the required pressure is fed by a pumpinto the housing. High pressure developed inside the housing enables thecoolant to penetrate directly to the tool cutting lips, whichconsiderably increases its endurance.

However, the arrangement of the workpiece to be machined inside thepressurized housing involves substantial time wasted ondepressurization, removal and positioning of the workpiece to bemachined, filling the housing with coolant and its pressurization, whichsignificantly reduces the process efficiency, while the provision of ahigh-lift pump renders the construction more expensive andsophisticated.

Still another device for supplying a lubricating-and-cooling agent tothe cutting tool is known to comprise a housing with an opening adaptedto receive an arbor with the cutting tool, a seal mounted on the housingin the zone of interaction between the cutting tool and the workpiecebeing machined, pipes for the coolant to be fed to and discharged fromthe housing, and an opening for chip disposal communicating with thehousing space (cf. German Patent No. 747,139). The housing is made inthe form of a bell resting with its lower portion on the surface of theworkpiece being machined.

Coolant is fed into the housing through a coolant supply pipe unionturned into the housing. The chip disposal opening and the coolantdrain-out opening are arranged above the supply pipe union. The positionof the chip disposal opening determines the height of the coolantcolumn. Static pressure produced by the coolant column causes thecoolant to penetrate into the holes being machined, thus increasing thecutting tool endurance.

However, the latter device described hereinbefore fails to produce asufficiently high coolant pressure due to the fact that the housing isnot pressurized, and the amount of pressure is only determined by theheight of the coolant column which, in turn, is restricted by thehousing dimensions. This results in low drilling efficiency. Besides,the device mentioned above is only practicable for vertical drilling.

SUMMARY OF THE INVENTION

The present invention is aimed at the provision of a device forsupplying coolant to the cutting tool, which is made in such a way as toensure a high static coolant pressure without the use of a high-liftpump, and is applicable for both horizontal and vertical drilling ofworkpieces having an arbitrary size and shape.

The above-said object is accomplished by a device for supplying coolantto the cutting tool, comprising a housing having a hole adapted toreceive an arbor carrying a cutting tool, a seal mounted on the housingin the zone of interaction between the cutting tool and the workpiecebeing machined, a piping for the supply of coolant into the housing, apiping for the discharge of coolant from the housing, and a chipdisposal opening communicating with the housing space, according to theinvention, the coolant withdrawal piping is provided with a safetyvalve, the housing is provided with a seal arranged in the zone of thearbor location, while the chip disposal opening and the housing spaceare arranged on the opposite sides of the housing end face in the zone,where the cutting tool interacts with the workpiece being machined.

The herein-proposed device makes it possible to increase the efficiencyof hole machining in workpieces of an arbitrary size and shape usingcutting tools, and to extend cutting tool endurance. This isaccomplished by the lubricating-and-cooling agent, under the action of asubstantially high static pressure produced within the housing, which isurged to penetrate to the cutting tool lips during both vertical andhorizontal machining. Since the workpiece to be machined is arrangedoutside the housing, its dimensions and shape have virtually no effecton the dimensions and volume of the housing.

It is expedient that a float valve be mounted on the housing, and anelectric-contact check valve be installed on the coolant supply pipe.

Such an arrangement enables fully automatic control of the processes offilling the housing with coolant, air bleeding, pressurization of thehousing, and feed motion of the cutting tool.

BRIEF DESCRIPTION OF THE DRAWING

In what follows the present invention will now be disclosed in adetailed description of an illustrative embodiment thereof withreference to the accompanying drawing, which is a diagrammatic view of adevice for supply of coolant to the cutting tool.

The sole FIGURE is an elevational view in partial section of anembodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The herein-proposed device comprises a housing 1 provided with a hole 2adapted to receive an arbor 3 carrying a cutting tool 4. The hole 2 hasa seal 5 for the arbor 3. A jig bush 7 having a seal 8 is installed inthe housing 1 in the zone of interaction between the cutting tool 4 anda workpiece 6 to be machined. A space 9 of the housing 1 is associatedwith an opening 10 for chip disposal. The chip disposal opening 10 andthe housing space 9 are arranged on opposite sides with respect to anend face 11 of the housing 1, in the zone of interaction between thecutting tool 4 and the workpiece 6 to be machined. The opening 10 isprovided with a cover 12 adapted to hermetically close the opening 10 inthe course of operation, through the agency of a seal 13. Closing andopening of the cover 12 is effected by a mechanism 14.

To provide for fully automatic control over the filling of the housing 1with coolant, air bleeding, pressurization of the housing 1, andengagement of feed motion of the cutting tool 4, the herein-proposeddevice is provided with a float valve 15 installed vertically on thehousing 1. Besides, an electric-contact check valve 17 is installed on acoolant supply pipeline 16. A safety valve 19 and a pressure gauge 20are installed on a coolant discharge pipeline 18.

The herein-proposed device operates as follows.

In the initial position, the arbor 3 is enclosed in the seal 5, theworkpiece 6 is held against the seal 8, and the cover 12 is closed.

A supply pump 21 fills the inner space 9 of the housing 1 with coolant,via the electric-contact check valve 17, thus expelling the air throughthe float valve 15. After the housing 1 has been filled up, coolantfinds its way to the float valve 15, the float comes to the surface sothat the valve 15 is closed. The pressure within the housing 1 and thatin the coolant supply pipeline 16 become equal and the electric-contactcheck valve 17 is closed, whereby a signal is delivered to engage thefeed motion of the cutting tool 4. As the arbor 3 is drawn into thehermetically closed housing 1, the coolant contained in the housing 1 iscompressed, whereby the pressure in the housing 1 builds up to thepressure setting of the safety valve 19. As soon as the preset pressurehas been reached, the pressure gauge 20 operates to stop the supply pump21. In case where the coolant pressure drops in the course of machining,the pressure gauge 20 disengages the feed motion of the cutting tool 4.

Once the machining process has been completed, the arbor 3 with thecutting tool 4 are withdrawn into the initial position, and themechanism 11 opens the cover 9, while chip and coolant are removed fromthe housing 1 through the opening 10. After replacement of the workpiece6 to be machined, the cover 9 is closed and the entire cycle isrepeated.

The herein-proposed device for supply of coolant to the cutting toolmakes ti possible to increase the efficiency and accuracy of machiningholes with blade-type tools, and, simultaneously, to extend theendurance of the cutting tool applied. Besides, the proposed device canbe used for both vertical and horizontal maching of workpieces ofarbitrary dimensions and shapes.

INDUSTRIAL APPLICABILITY

The herein-proposed invention finds particular utility when employed fordeep-hole drilling with the aid of twist drills.

We claim:
 1. A device for supplying coolant to a cutting toolcomprising:a housing defining a space and having an end face, a holeadapted to receive an arbor carrying a cutting tool, a first sealmounted on the end face in a zone of interaction between the cuttingtool and a workpiece being machined, a first piping for transportingcoolant to the housing, a second piping for withdrawing coolant from thehousing, a chip disposal opening communicating with the space, saidopening and said space arranged on opposite sides with respect to theend face of the housing in the zone of interaction, a safety valveoperatively connected to the second piping, and a second seal in thehole adapted to receive the arbor.
 2. The device of claim 1 furthercomprising a float valve and an electric-contact check valve operativelyconnected to the first piping.